The present invention relates to a device for limiting a working stroke of a hydraulic cylinder, especially for pressing devices, wherein the working cylinder may be actuatable from both ends.
From German Offenlegungschrfit 23 23 522 a stroke-dependent valve device for limiting the working stroke of the piston of an auxiliary power steering device is known. When the stroke end position is reached, a short circuit between the pressure and the suction side of the pressure medium pump is generated by opening a valve. For the actuation of the valve control cams are provided that are drivingly connected with the working piston. When the prescribed stroke end position is reached, the control cams shut off a pressure force which maintains the control slide together with a spring in a non-operating position which prevents the short circuit of the pump. The constructive expenditure for the valve and the lines for shutting off the working pressure in this embodiment are relatively great in this known device.
It is therefore an object of the present invention to provide a constructively and functionally simple device for limiting the stroke of a piston of a working cylinder, which may be combined with the working cylinder to one constructive unit in a compact design, which requires only constructively simple actuating elements, and with which a hydromechanical positioning control circuit may be accomplished by simple means. Furthermore, the device should be embodied such that the stroke limitation with respect to timing and positioning of the piston may be simply adjusted within given limits.